ANOMALOUS ABSORPTION OF VERY HIGH-INTENSITY LASER-PULSES PROPAGATING THROUGH MODERATELY DENSE-PLASMA

The results of a systematic study of the propagation of very high-inte nsity laser pulses through slabs of plasma of several tens of microns are presented; One-dimensional and two-dimensional electron parametric instabilities are evidenced. They lead to a rapid longitudinal and tr ansverse heating, and to filamentary structures which progressively me rge. The heating results in highly energetic electrons with energy of several tens of MeV. Correlatively, a strong attenuation rate of the e lectromagnetic wave is observed.